The research described in this application will test the hypothesis that the renal nerves represent an important afferent and efferent control system for the regulation of several renal functions. Using a combination of renal clearance, micropuncture, hemodynamic and electrophysiologic nerve recording techniques, studies will be conducted in both anesthetized rats and dogs as well as conscious unanesthetized rats. The individual experiments: will examine whether renal tubular sodium reabsorption in more distal nephron segments (e.g., loop of Henle) is influenced by efferent renal sympathetic nerve activity, will test the dependence of the normal renal adaptive response to chronic dietary sodium deprivation on intact renal innervaton, will evaluate the role of efferent renal sympathetic nerve activity in various sodium-retaining edema-forming states, will further define the nature of the renal tubular alpha adrenoceptor which mediates the neurogenic antinaturiuresis, will evaluate the functional role of reno-renal reflexes and assess the ability of environmental induced changes in efferent renal sympathetic nerve activity to influence renal function. These studies represent a multifaceted physiological and pharmacological approach to the study of the neural control of renal function.